So i took a look at the source.
It is in german, one of the languages spoken in Luxembourg.
There are multiple warnings on the page that this is a mod that breaks the approval of these routers, and only radio amateurs might do this.
Ofcoure you also need to check local regulations on this.
The reason for doing this mod is the fact that the frequenties are used by multiple systems, bluetooth for instance.
What you would be doing is to shift the frequenties, if you follow the example you'd go about half the frequency range down (check the table).
Subsequently i'd say, you can only use this mod if you do this to two routers and put them in WDS.
It will eliminate other devices interfering with yours.
As stated above you might be the one interfering after this mod, so ensure you are not going to get in trouble by it.

I see no reason why this would not work.
And you might want to shift up instead of down, it's a matter of what components are available, and mentioned iterference.
It will not be a very easy mod.

As with all mods neither the author of the original site or me can or will be held responsible in case you are going to try this for yourself (and the consequenses of that).